1. Field of the Invention
The present invention relates to data transmission, and, in particular, to optical switches and optical circulators used in light-based data transmission.
2. Description of the Related Art
In light-based data transmission systems, such as terrestrial or undersea fiber-optic communication systems, optical switches are used to selectively route light energy through a network of optical-fiber paths. For example, a three-port optical switch (having ports 1, 2, and 3) might be configured to receive light energy at port 1 and selectively route the received light energy either to port 2 (i.e., 1.fwdarw.2) or to port 3 (i.e., 1.fwdarw.3).
Some conventional optical switches are opto-mechanical switches that rely on physical movement of optical fibers to alter the state of the switch. For example, in the aforementioned three-port optical switch, the state of the switch may be changed from (1.fwdarw.2) to (1.fwdarw.3) by physically moving the optical fibers corresponding to paths 2 and 3, such that fiber 3 replaces fiber 2 at the output port of the switch. Such opto-mechanical switches tend to have reliability problems related to the mechanical nature of the switching function. These reliability problems can be especially problematic when the optical switch is part of an undersea communication system, in which case it is particularly inconvenient to repair or replace a faulty switch.
Another type of optical switch is the magneto-optical switch, in which the state of the switch is controlled by electromagnetic components within the switch. For example, the polarity of the magnetic field generated by one or more electromagnets can be used to dictate the state of the switch. One advantage of magneto-optical switches over opto-mechanical switches is that there are no moving parts that can contribute to reliability problems.